The invention relates to an absorber for damping vibrations of a rotating component, in particular a cylinder or a roller of a rotary printing machine.
Vibration absorbers or dampers of this type have become known heretofore from a large number of publications. Such vibration absorbers or dampers are used, for example, in the drive train of internal combustion engines. In this context, what is understood by the designation xe2x80x9cabsorberxe2x80x9d is a device which only damps torsional vibrations in a component, without transmitting torque to another component.
The purpose of such vibration absorbers is to reduce torsional stresses in rotating components, in order to prevent damage to the components. Furthermore, in printing machines, absorbers also serve for preventing vibrations which influence the entire system and are detrimental to the quality of the printing result.
Vibration absorbers are known from the prior art which have elastic media as a damping and spring coupling member, for example, a spring ring made of rubber (note the published European Patent Document EP 0 647 796 A1). The vibration absorber described therein includes an inertia ring which has at least one spring ring made of rubber that is fixed relatively rotatably in a shaft and comes into direct bearing contact with the outer circumference of the shaft and is pressed nonrotatably onto the shaft by the inertia ring. Other types of damping and spring coupling members are also known.
In those absorbers which are used in printing machines, the following applies: the torsional inertia and torsional rigidity of the absorber are coordinated with one another in such a way that the characteristic frequency of the absorber corresponds to the characteristic frequency of the printing machine. The angular velocity of the rotational mass of the absorber is equal to the angular velocity of the rotating component, generally the impression cylinder. Under corresponding excitation, the characteristic vibration of the absorber mass is superposed on the rotational movement of the absorber mass. Relative rotation occurs, in this regard, between the absorber mass and the cylinder. This amounts to a maximum of 1xc2x0 during operation.
In a heretofore known construction, the absorber mass is mounted on the component by a roller bearing. It was shown, in this regard, that the useful life of such bearings may be relatively short. Attempts were made to solve the problem of lengthening the useful life by a choice of stronger bearings, but this has proven to be unsuccessful.
It is accordingly an object of the invention to provide an absorber of the type described in the introduction hereto, with a roller bearing between the absorber mass and the rotating component, which is of such construction that the useful life of the bearing is markedly longer than in conventional embodiments.
With the foregoing and other objects in view, there is provided, in accordance with the invention, an absorber for damping vibrations in a rotating component, comprising a primary part connectable to the rotating component so as to be fixed against rotation relative thereto; an absorber mass; the primary part and the absorber mass being couplable to one another via a damping and spring coupling so that the absorber mass is rotatable to a limited extent relative to the primary part; at least two antifriction bearings for mounting the absorber mass on the rotating component; the two antifriction bearings being nested within one another, so that one of the antifriction bearings is seated on a larger radius than the other; and an intermediate ring disposed in a radial direction between the two antifriction bearings.
In accordance with another feature of the invention, the rotating component is a cylinder of a rotary printing machine.
In accordance with a further feature of the invention, the intermediate ring forms an outer running surface of an inner bearing of the antifriction bearings, and an inner running surface of an outer bearing of the antifriction bearings.
In accordance with an added feature of the invention, the intermediate ring is connected to an outer race of the inner bearing and to an inner race of the outer bearing so as to be fixed against rotation relative thereto.
In accordance with an additional feature of the invention, the inner and the outer bearings constitute a first bearing pair, and including, axially adjacent the first bearing pair, a second bearing pair having bearings likewise nested within one another; and an intermediate ring also disposed between the bearings of the second bearing pair.
In accordance with yet another feature of the invention, the intermediate ring of one of the two bearing pairs is connected via a holder to fixed surroundings so as to be fixed against rotation relative to the fixed surroundings, and a web is included for connecting both of the intermediate rings to one another so that the intermediate rings are fixed against rotation relative to one another.
In accordance with a concomitant feature of the invention, the intermediate rings are formed as a single intermediate ring assigned to both of the bearing pairs.
The applicant-inventor has recognized the following: The relative rotation between the inner ring and the outer ring of the bearing is minimal. The rolling bodies, such as balls, rollers or needles, of the bearing execute virtually no rolling movement. They therefore dwell virtually at one and the same point. It is consequently always the same points on the running surfaces of the bearing which are subjected to stress, so that xe2x80x9cpotholesxe2x80x9d of a kind are formed. Moreover, the rolling bodies are permanently subjected to a load which acts in a single direction and on a single region, thus leading to premature failure of the bearing.
By virtue of the arrangement according to the invention, with two bearings nested one within the other and with a common intermediate ring secured against rotation, rotation of the rolling bodies occurs.
The principle according to the invention can be implemented very simply and without a high cost outlay and integrated into the vibration absorber. It can also be implemented as a fixed/loose or movable bearing.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in an absorber for damping vibrations in a rotating component, in particular in a rotary printing machine, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.